Call con_activate after moving scratchpad window to current ws

Fixes #3361

src/scratchpad.c

@@ -141,6 +141,7 @@ bool scratchpad_show(Con *con) {
             DLOG("Found a visible scratchpad window on another workspace,\n");
             DLOG("moving it to this workspace: con = %p\n", walk_con);
             con_move_to_workspace(walk_con, focused_ws, true, false, false);
+            con_activate(con_descend_focused(walk_con));
             return true;
         }
     }